Switch mechanism



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Q. A. COLBY ET AL,

SWITCH MECHANISM Filed Dec, 2, 1920 WITNESES:

' Patented Dec. 30, 1924.

UNITED STATES PATENT OFFICE.

ORA A. COLBY, or IRWIN, AND EARL w. DENMAN, or SWISSVALE, PENNSYLVANIA,

ASSIGNORS T0 WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A con-]?ORATION OF PENNSYLVANIA.

SWITCH MECHANISM.

Application filed December 2, 1920. Serial No. 427,779.

To all whom it may concern;

Be it known that we, ORA A. COLBY, a citizen of the United States, and aresident of Irwin, in the county of Westmoreland and State ofPennsylvania, and EARL W. DENMAN, a citizen of the United States, and aresident of Swissvale, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in SwitchMechanism, of which the following is a specification.

Our invention relates to switch mechanism and particularly to switchmechanism of the knife-blade type wherein an electriccircuit is closedby engagement of a switchblade member with stationary contact-jaw.

members.

An object of the invention is to provide a switch mechanism wherein thearcing incident to the opening of the switch is reduced to a-minimum orto a point where the arc is not injurious to the blade member or to thecontact-jaw members.

Another object is to provide a switch mechanism having the abovecharacteristics wherein the arc-extinguishing member serves as aprotective housing for the switch member.

A further object is to provide a switch for the purpose above statedthat is efficient and dependable and which is simple and inexpensive tomanufacture.

It is well known that the arcs incident to the opening of a switch arefrequently destructive to the switch blade and the contact jaws, and toreduce their damaging effects, switches have been so made that they openand close with a snap action, thereby reducing the duration of the are.However, under certain conditions, the opening of the switchwith a snapaction does not extinguish the are before it has had opportunity to fuseor pit the switch blades and the contact-jaw members, and where suchpitting occurs the blades and jaw members soon become defective.

The objects above recited and others that will be made apparentthroughout the further description of the invention are attained bymeans of the switch mechanism hereinafter described and illustrated inthe accompanying drawings, wherein:

Fig. 1 is a plan view of an improved switch mechanism embodying ourinvention.

Fig. 2 is a longitudinal vertical section on the line TL-II of Fig. 1.

Fig. 3 is a longitudinal vertical section on the line III-TH of Fig. 1,viewed in the direction of the arrows.

Referring to the drawing, the switch mechanism therein illustrated is ofthe type used in controlling car-heating systems. The switch is of therotary snap-action type and is operated by a motor that is preferablycontrolled by a thermostat. The controlling swltch is so connected withthe operating motor and the motor is so connected to the terminals ofthe thermostat (not shown) that, when the temperature of the car orbuilding in which the device is installed eX ceeds a determined degree,the circuit through the motor is closed by the thermostat and the switchis actuated a quarter turn into a position wherein the circuits throughthe heating system and throu h the motor are simultaneously interrupted.

\Vhen the temperature of the medium surrounding the thermostat isreduced to a predetermined degree, the circuit through the motor isagain closed by the thermostat and the switch is rotated a quarter turninto a position wherein the circuit through the heater is closed andthat through the motor is opened. This system of control is not a partof our invention, and it is believed that a detailed description of itsapplication is not necessary herein.

As shown, the apparatus includes a housing' 4 having a bottom casting 5to which a switch-supporting bracket 6 is secured. The switclrmechanism,which is mounted for rotation in this bracket, comprises a rotary shaft7 to which an insulating hub 8 is secured. This hub carries theswitchblade member 9. The switch blade is rotated by means of anelectric motor 10 that is controlled by the above-mentioned thermostatswitch (not shown).

The motor is geared to the switch shaft 7 through a train of reductiongearing 11 by means of which the shaft 7 is rotated by the motor at agreatly reduced speed. It will be understood, for the purpose of thisdescription, that the switch is of the snapaction type adapted to beactuated a quarter turn with a snap action in response to apredetermined rotary movement of the motor.

The features that are new and novel are included in the arrangement ofthe parts constituting the arc extinguishing mechanism. This apparatusincludes an insulating base 12 that is adapted to support the switchterminals or binding posts 13 and the lowermost switch contact-jawmembers 14, that are severallysupported in recesses 15 located in theunderside of the base. These contact-jaw members are'connected withtheir respective terminals 13 by means of any suitable conductors and inany manner desired, depending upon the system of control to which theswitch is applied. The base is provided with a circular opening 16,through which the switch hub 8 extends, and the blade member 9 of theswitch mechanism is located as close to the upper surface of the baseas'it is practical to operate it without rubbing the base. I

An insulating disc or cap 17 is mounted on the base 12 and entirelyencloses the switch member 9, which is free to rotate within the shallowchamber 18, which is provided between the cap and they base. It will beobserved that just sufiicient space is provided between the oppositesides of the blade member and the wa s of the chamber 18 to rmit freerotation of the blade. The cap 1 is provided with a series of rec.-tangular openlngs 19 spaced equidistantly about the axis of the switchand so positioned that the adjacent openings are disposed at rightangles to one anot er. The ends 20 of the openings are countersunk orinclined toward the center thereof and thus form knife edges 21 at theinner edges of the openings, the purpose of which will hereinafterappear.

The base 12 is also provided with a similar series of openings of likeformation which register with those in the cap 17; the perforationsopening out of, and communicating with, the recess 15 in the base. Therelative position is clearly illustrated in Figure 3.

The u per contact-jaw members 22 are connected to their respective lowercontactjaw members 14 by means of the connecting mechanism illustratedin Fig. 3, which comprises a bolt 23 having'an enlarged end 24 so-tappedas to receive a binding screw 25 which connects it with the conductorthat leads to, and is connected with, the terminals 13. The contact jaw14 is mounted upon the shank 27 of the bolt and is dis osed between awasher 28 and theenlarge head 24.

The bolt 23 is tightly clamped to the base 12 by means of the internallythreaded sleeve 29. This sleeve supports the contactjaw member 22, whichis a plied to the bolt shank after the cap 17 has been put in place uponthe base 12. An oblong washer 30,

which is placed over the contact 22, serves to engage and retain the cap17. The washer and contact-jaw 22 are retained in position by means ofthe screw 31.

It will be seen from the foregoing that the switch-blade member 9 turnswithin the chamber 18 and moves to a position between the yieldingcontact-jaw members 14 and 22. The snap mechanism (not shown) is adaptedto move the "blade members a quarter turn with a snap action in res onseto a predetermined movement of the s aft 7, and to stop the blade member9 when the ends thereof are in engagement with the contactjaw members,as illustrated in Fig. 3.

When the blade members move out of engagement with the contact-jawmembers, the arc resultin from the separation of the blade member romthe jaw members tends to follow the blade and to expand s heri- Aportion of the are entering the chamber 18 is so flattened and itssurface so extended that it is immediately chilled by contact with theinner walls of the chamber andthus reduced and extinguished. Theexplosion caused by the are within the limited confinesof the chamber 18causes the gases of combustion to be violently discharged from theopenings 19 at a high velocity, with the result that the arc is blownaway from the blade.

From actual test it has been found that switches made in accordance withour invention may be operated safely without the least injur to theblades or contact members under loa many times their rated capacity.This feature enables a hi her capacity rating to be placed on switchlades and contact-jaws which have heretofore been rated, not as to theircurrent-carrying capacity, but as to their are resting capacity, for itis well known that the former greatly exceeds the latter.

As a result of this construction, switch blades and contact-jaw membersmay be materially reduced in weightwith a correspondin reduction in costof materials. The dura ility of the switch is increased because of theabsence of a destructive arc.

While we have described and illustrated but one embodiment of ourinvention, it will additions and omissions-may be made in the apparatusdescribed without departing from the spirit and scope of the invention,as set forth by the appended claims.

We claim as our invention:

1. The combination with co-operating contact members, of an insulatinghousing enclosing one only of the members and constituting a shallowchamber in which that member operates, the said housing being providedwith a gas-escape opening through which the other contact member extendsinto the chamber.

2. The combination with a stationary contact member and a coactingswitch member movable in a predetermined plane, of a housing havingclosely spaced walls for enclosing the switch member within a shal- 1low chamber in which the switch member opcrates and having a ventadjacent the contact member, the walls of the chamber beingsubstantially parallel with the plane of movement of the blade and inclose proximity to the blade.

3. Switch mechanism comprising a housing having a shallow switchchamber, a movable switch member within the chamber, and contact jawstherefor projecting into the chamber through an opening permitting theescape of gases from the chamber.

4. Switch mechanism comprising a housing having a shallow switchchamber, a movable switch member within the chamber, and contact jawsfor the switch member secured to the exterior of the housing andprojecting into the said chamber.

5. Switch mechanism comprising a housing having a shallow switchchamber, a movable switch member within the chamber and contact-jawmembers for receiving the switch member secured to the housing andprojecting into the chamber through countersunk openings in the housing.

6. Switch mechanism comprising a housing having a shallow switch chamberprovided with spaced openings, a switch member mounted within thechamber and movable into registry with the said openings, and contactmembers extending through the openings into engagement with the saidswitch member,

7. The combination with a contact member anda coacting knife blademember, of a pair of shield members havin a space therebetween throughwhich the b ade member operates and having the entrance edges thereof soinclined as to form cutting edges on opposite sides of the blade memberadj acentthe point of engagement of the blade member with the contactmember.

8. The combination with a contact member and a coacting switch member,of ahousing for enclosing the switch member having openings in thevicinity of the contact member through which compressed gases generatedwithin the housing may escape.

9. The combination with a contact member and a coacting switch member,of a housing for the switch member comprising a heat-absorbing bodyprovided with a shallow chamber in which the switch member operates andhaving a vent adjacent the contact member, the inner walls of thechamber on opposite sides of the switch member being disposed in closeproximity to the switch member and adapted to permit the escape of gasesonly through the said vent whereby arcs incident to the openin of theswitch are directed toward the said vent and cooled by thesaid walls.

10. Switch mechanism comprising an insulating base, a contact member, arotatable shaft member, a switch member mounted on the shaft memberadjacent one face of the base and for rotary movement into and out ofengagement with the contact member in a plane parallel to the adjacentface of the base, and an insulating cover for the switch member closelyfitting about the shaft member and co-operating with the base to form a.shallow chamber therebetween in which the switch member operates,whereby arcs incident to the opening of the switch member are confinedand chilled.

11. Switch mechanism comprising a pair of insulating plates having ashallow annular chamber therebetween, contact-jaw members disposed onthe outer faces of the plates and extending into the chamber throughperforations therein, and a switch member within the chamber movableinto and out of engagement with the contactjaw members.

12. Switch mechanism comprising a contact member, a rotatable switchmember movable into and out of en agement with the contact member, a shat member for supporting the switch member, and a pair of heat-absorbingplates closely fitting about the shaft member and having their adjacentfaces disposed in close proximity to the switch blade and on oppositesides thereof whereby the arc incident to the opening of the switchmember is confined between the plates and chilled.

13. The combination with a stationary contact member and a coactingswitch member movable in a predetermined plane, of a housing forenclosing the switch member comprising a pair of insulating platesconstituting a shallow chamber in which the switch member operates andis retained in assembled relation by the contact member, the walls ofthe chamber being substantially parallel with. the plane of movement ofthe blade and iii close proximity to the blade.

In testimony whereof, we have hereunto subscribed our names this 30thday of No vember, 1920.

ORA A. COLBY. EARL W. DENMAN.

